In Reply: The criteria for validity assessment
in our systematic review are based on guidelines that have been recently updated
and peer reviewed by international experts in systematic review methodology.1

To take each of Dr Goudsmit's points in turn:

First, Goudsmit's trial was nonrandomized, and compared an intervention
group that had been diagnosed by a specialist to a waiting list control who
had not been diagnosed. Consequently, the groups were likely to differ in
terms of presence or severity of CFS. The groups were also unmatched for duration
of illness, time on the waiting list and employment status.